In the past, there have been proposed a variety of kinds of constructions in array antennas apparatuses (for example, refer to a first patent document and a first nonpatent document).
A conventional array antenna apparatus as shown in the first patent document is provided with a plurality of antenna elements, a plurality of transmission and reception modules that are connected to the individual antenna elements, respectively, and a distributing and synthesizing device that distributes transmission intermediate frequency signals to the plurality of transmission and reception modules (or synthesizes reception intermediate frequency signals from the plurality of transmission and reception modules).
In addition, each transmission and reception module is provided with a first duplexer that sends a transmission high frequency signal to each antenna element (or receives a reception high frequency signal from the antenna element), a transmission amplifier that amplifies the transmission high frequency signal and sends it to the duplexer, a reception amplifier that amplifies a reception high frequency signal from the duplexer, a second duplexer that sends the transmission high frequency signal to the transmission amplifier (or receives the reception high frequency signal from the reception amplifier), a mixer that is combined with the second duplexer and produces the transmission high frequency signal from a local oscillation signal and an intermediate frequency signal from the outside (or produces a reception intermediate frequency signal from the local oscillation signal and the reception high frequency signal), and a local oscillation signal generator.
In the above-mentioned construction of the first patent document, a clock signal and a trigger signal are inputted to the local oscillation signal generator from the outside, so that the synchronization of local oscillation signals generated by the individual transmission and reception modules is taken therein.
In this manner, transmission loss at the time of distributing and combining or synthesizing signals or supplying electric power to the modules is suppressed by using intermediate frequency signals instead of high frequency signals as the transmission and reception signals which are inputted to or outputted from the transmission and reception modules of the array antenna apparatus.
On the other hand, in the case of another conventional array antenna apparatus as shown in the first nonpatent document, in a transmission array, antenna elements are grouped into a plurality of groups, each of which comprises a plurality of antenna elements arranged in proximity with one another, and the antenna elements of each group are connected to one another through a signal distributor which is composed of a plurality of transmission signal generators and a cross point switch.
In the above-mentioned construction in the first patent document, it is constructed such that the transmission high frequency signals generated by the transmission signal generators are distributed to supply electric power to the antenna elements of arbitrary groups, wherein by dividing an aperture plane of a transmission array antenna, the thus divided parts thereof are assigned to a plurality of communications, electronic warfare systems, radars, etc., respectively, so that they can be used at the same time.